1959-1979: As a tiny city-state bent on developing industry, housing stock, and roads, Singapore confronts air and water pollution and waste disposal challenges. In the early '70s the government creates an anti-pollution unit in the Prime Minister's Office, sets up the Ministry of the Environment, and passes its first environmental laws.

1980-1989: High-density development helps Singapore successfully manage garbage disposal and wastewater treatment. Tough laws and a preference for "clean" industries help mitigate the toll from a transportation boom. By 1989, five expressways crisscross Singapore. The government taxes gasoline and cars and opens a $5 billion mass-transit bus system.

1990-1995: Singapore is a party to the 1992 United Nations Conference on Environment and Development in Rio de Janeiro, which drafts conventions on climate change, hazardous wastes, ocean pollution, and other green issues. It refrains from signing the 1992 Kyoto protocols. In 1993 Singapore prosecutes 36 industries for illegal discharges into the sewer system.

1996-2003: Singapore is the world's most densely populated area, yet it remains without a central environmental authority. Air and water quality compare favorably with the world's cleanest cities, but forest fires in Indonesia threaten both. Singapore earns high marks for environmental management.